"There's no honour in pooing yourself to death, so no one wants to talk about the fact that dysentery killed more people than bullets and bombs," Crocetti told HuffPost Australia.

"We went to some of the remaining trenches in France and spoke to experts at places like Cambridge University, all the war memorials and no one wanted to talk about dysentery."

So, in The Invisible War, dysentery becomes the enemy and the hero? Well it's a 'friendly' virus called a bacteriophage that attacks bacteria, not human cells, effectively shielding the body from harm.

"With the commemoration of the WWI centenary, we realised that at the same time, it was also the centenary of the discovery of bacteriophages," Crocetti said.

"We thought 'why not tell both stories at the same time -- the war of WWI and the inner, invisible war."

Crocetti said the project gave him a greater respect for nurses.

"Originally, the story was going to be told through the eyes of a soldier but right away we realised it was the nurses who saw the effects of dysentary, and they were also the ones who could explain it," Crocetti said.

"Nurses play a vital role in war and they do the messy, dangerous, hard jobs still today.

"There's a very graphic scene in the story where a nurse is on the toilet and she's looking at her poo and she's thinking 'please god don't have blood in it'. A nurse knows what it means to have blood in your stool, a soldier doesn't.